Mycological Research News features what Phytophthora infestans race caused the Irish Potato famine?

Molecular work in this issue compares Glomus isolates from mycorrhizal roots and soil in the same field and reveals some discrepancies and probably novel taxa. New mt SSU rDNA primers hae been designed for use in filamentous ascomycetes and applied to Botryosphaeria and related anamorphs. β-tublin gene seqeuences are used in a phylogenetic study of species of Calonectria and associated Cylindrocladium anamorphs.

Microsatellite DNA analysis is used to examine variation in several fungi: a single clonal lineage of Phytophthora cinnamomi from different trees shows asexually derived morphological and pathological variation; Coniothyrium minitans proves to be rather invariable at the molecular level; five microsatellite loci in Dothiostroma pini generated with an anchored PCR technique enable most isolates to be differentiated; and in Beauveria brongniartii, ten microsatellite markers have been identified with the potential for monitoring biocontrol.

An analysis of substrate preferences amongst aquatic hyphomycetes indicates that some substrates support relatively specialized assemblages of species. The establishment of arbuscular mycorrhizas in the saltmarsh plant Puccinellia nuttalliana is shown to be limited by edaphic factors and not the presence of a suitable host. Further studies on the occurrence of three fungi on pine needles along a climatic gradient in France are reported. β-carotene has been found to inhibit sclerotium differentiation in Sclerotinia sclerotiorum, and epifluorescence microscopy has been used to study the galls formed by Biatoropsis usnearum.

Taxonomic papers included present six further Biscogniauxia's from Taiwan (with a key to the world species), assess the positions of Poronia pileiformis and Xylaria cranioides based on cultures of the anamorphs, report on new species of Inocybe in Spain, revise Entoloma species with cuboid spores in Madagascar (with a key to 13 taxa), and survey the species of Tulasnella in the Patagonian Andes.

The following new scientific names are introduced: Biscogniauxia ambiens, B. cylindrospora, B. formosana, B. latirima, Entoloma pseudoheimii, E. rufovinascens, Inocybe barrasae, I. ortegae, and Tulasnella robusta spp. nov.; B. abosticta var. orientalis, and B. formosana var. kentingensis vars. nov.; E. cuboidosporum var. chromostomum (syn. Rhodophyllus cuboidosporum var. chromostomum), and E. heimii (syn. R. heimii) combs. nov.

The molecular diversity of glomalean fungi was studied by analysis of Glomus specific sequences amplified from field harvested peas. Glomus specific, large rDNA sequences were amplified from roots in a nested PCR reaction, following primary amplification with eukaryote specific primers. The nested primers were designed to amplify a lineage within the genus Glomus including G. mosseae, G. caledonium and G. geosporum, all of which had repeatedly been isolated from trap cultures set up with soil from the field. Single-stranded conformation polymorphism (SSCP) was used to screen the nested PCR products for presence of multiple sequence types. Nested PCR products were sequenced if necessary after reamplification of single SSCP types. The root derived sequences were aligned with sequences from spores of 17 cultured Glomus isolates; five of these isolated from the same field from where the peas were harvested. Some of the root-derived sequences were from lineages other than those species isolated from the field and some of the isolated species were not retrieved as sequences from the roots.

Two PCR primers (MSU1 and MSU7) were designed to amplify part of the mt SSU rDNA gene from filamentous ascomycetes. The MSU1-MSU7 and MSU1-NMS2 primer pairs were tested with 32 isolates of 23 species in 10 genera. Minimum evolution, parsimony, and likelihood methods were used for the phylogenetic analyses of mt SSU rDNA sequences from Botryosphaeria species and related taxa. These analyses indicated that: Botryosphaeria is not monophyletic; the separation of Botryosphaeria from Guignardia is supported; except for B. vaccinii, other Botryosphaeria species and related taxa form a monophyletic group with strong jackknife support; Diplodia pinea f. sp. cupressi is different from RAPD marker groups A and B of Sphaeropsis sapinea; the anamorph genera Sphaeropsis and Diplodia are not indicative of close relationships among different species; and the name B. stevensii may have been applied to more than one species. Botryosphaeria needs additional study and substantial taxonomic revision.

Species of Calonectria represent an important group of plant pathogenic fungi that cause serious losses to crops in tropical and subtropical climates. Because these fungi are difficult to identify, selected species were subjected to DNA analysis with the aim of producing a more objective identification technique. This was done by amplifying the 5′ end of the β-tubulin gene from isolates representing more than 30 species of Calonectria. A neighbour joining analysis was performed on a total data set of 86 isolates, while a representative subset of isolates was analysed by means of maximum parsimony. Both analyses yielded dendrograms with concordant topology. Several clades were strongly supported by bootstrap, confirming the morphological and biological species concepts presently employed. At least two large groupings were evident and both contained small-spored, 1-septate species. The only morphological character that correlated with DNA phylogeny was vesicle shape. These data support Calonectria as a monophyletic genus with Cylindrocladium anamorphs. Furthermore, this study also emphasises the importance of vesicle morphology in identifying Cylindrocladium anamorphs, and hence species of Calonectria.

Seventy-three isolates of Phytophthora cinnamomi were collected from diseased Eucalyptus marginata (jarrah) and Corymbia calophylla (marri) trees in two forest communities in the southwest of Western Australia. Both populations of P. cinnamomi were examined for phenotypic and genotypic variation. Microsatellite DNA analysis showed that all isolates were of the same clonal lineage. We show, for the first time for P. cinnamomi, that morphological and pathogenic variation between populations of the clonal lineage are very broad and continuous. The phenotypes examined included growth rates and colony morphology on potato dextrose agar at different temperatures, sporangial and gametangial morphology, ability to form lesions in detached jarrah and marri stems, and ability to cause deaths of clonal jarrah plants in a glasshouse trial. Phenotype variation was derived asexually. All phenotypes investigated varied independently from one another. Cluster analysis of 24 morphological and pathogenicity phenotypes identified two main clusters of isolates corresponding to each population. The ability to cause deaths in both populations ranged from killing all plants within 59 d to plants being symptomless 182 d after inoculation.

Simple sequence repeat (SSR)–PCR amplification using a microsatellite primer (GACA)4 and ribosomal RNA gene sequencing were used to examine the intraspecific diversity in the mycoparasite Coniothyrium minitans based on 48 strains, representing eight colony types, from 17 countries world-wide. Coniothyrium cerealis, C. fuckelii and C. sporulosum were used for interspecific comparison. The SSR–PCR technique revealed a relatively low level of polymorphism within C. minitans but did allow some differentiation between strains. While there was no relationship between SSR–PCR profiles and colony type, there was some limited correlation between these profiles and country of origin. Sequences of the ITS 1 and ITS 2 regions and the 5.8S gene of rRNA genes were identical in all twenty-four strains of C. minitans examined irrespective of colony type and origin. These results indicate that C. minitans is genetically not very variable despite phenotypic differences. ITS and 5.8S rRNA gene sequence analyses showed that C. minitans had similarities of 94% with C. fuckelii and C. sporulosum (which were identical to each other) and only 64% with C. cerealis. Database searches failed to show any similarity with the ITS 1 sequence for C. minitans although the 5.8S rRNA gene and ITS 2 sequences revealed an 87% similarity with Aporospora terricola. The ITS sequence including the 5.8S rRNA gene sequence of Coniothyrium cerealis showed 91% similarity to Phaeosphaeria microscopica. Phylogenetic analyses using database information suggest that C. minitans, C. sporulosum, C. fuckelii and A. terricola cluster in one clade, grouping with Helminthosporium species and ‘Leptosphaeria’ bicolor. Coniothyrium cerealis grouped with Ampelomyces quisqualis and formed a major cluster with members of the Phaeosphaeriacae and Phaeosphaeria microscopica.

A microsatellite-based DNA profiling system was developed that can be used to distinguish genetically diverse isolates of a forest pathogen, Dothistroma pini. All isolates of this pathogen identified in New Zealand so far appear to be isogenic and the disease is kept under control by aerial applications of copper fungicide. Although New Zealand has strict importation controls in place, the possibility of genetically diverse isolates of D. pini being introduced from other countries poses a severe biosecurity threat to forest health. Therefore a DNA-based monitoring system was developed. Two informative microsatellite loci were found serendipitously in D. pini sequence data available in our laboratory. Further microsatellite loci were obtained using a rapid 5′-anchored PCR amplification technique. For each informative locus identified, specific primers were designed to flank the repeated sequence and subsequently used to generate DNA profiles for the D. pini strains. The profiles obtained from five microsatellite loci were sufficient to distinguish most isolates tested. The anchored primer technique provides an efficient tool for the identification of polymorphic loci that can be used to screen for genetic differences between fungi.

We have identified ten microsatellite markers in the entomopathogenic fungus Beauveria brongniartii from three genomic libraries enriched for (AAG)n-, (TG)n-, or (TC)n-repeats. The levels of polymorphism of the identified microsatellite loci were assessed in a collection of Beauveria strains originating from different countries, areas, and host insects. Two geographically separated Swiss populations of B. brongniartii originating from European cockchafer (Melolontha melolontha) were also analysed. Microsatellites containing (AAG)n-repeats generally displayed high levels of polymorphism, whereas microsatellites containing either (TG)n- or (TC)n-repeats displayed lower levels of polymorphism. Cluster analysis revealed that strains isolated from M. melolontha larvae, and two strains isolated from Melolontha hippocastani or Amphimallon solstitiale larvae, formed one cluster which was separated from strains isolated from adult M. melolontha and other adult insects. A high degree of biodiversity was detected among B. brongniartii strains of the two separated Swiss populations. Distinct haplotypes were identified in 29 of 35 B. brongniartii strains from population A and in 12 of 28 B. brongniartii strains from population B. The high discrimination power of the identified microsatellites makes them a valuable tool, suited for the characterization and identification of B. brongniartii strains used as biocontrol agents. In addition, they may be applied to monitor biological control strains of B. brongniartii in the field and possibly to investigate their interactions with indigenous B. brongniartii isolates.

Aquatic hyphomycete assemblages on different types of plant litter in Belarus rivers and streams were investigated to determine whether any substrate specificity or preferences were apparent. Pooled samples (146) from 92 watercourses were analysed. Colonization coefficients were computed for each fungal taxa and substrate type and the resulting matrix analysed with principal component analysis and cluster analysis. The results demonstrate that some substrates support relatively specific aquatic hyphomycete assemblages and it is possible to ordinate plant litter types by means of their fungal complexes. This suggests selective colonization by fungi, i.e. substrate preferences at least in some species. Wood and grass blades bear fungal assemblages clearly distinct from those supported by tree leaf litter (with higher percentage of scolecosporous and antagonistic species). Ordination of plant litter types could be explained by size of substrate units, their chemical composition (in particular lignin content) and, consequently, breakdown rate that affects fungal colonization.

This paper develops field data analysis and theoretical hypotheses concerning the role of climatic factors and fungal interactions in the control of fungal populations. We studied three ‘resource unit restricted fungi' colonizing Pinus sylvestris needles along a climatic gradient. We investigated both competition and succession. A general linear model was used for statistical analysis. Despite interference competition at the scale of the individual needle, the first two colonizers, Lophodermium pinastri and Cyclaneusma minus, coexisted and the frequencies of both increased with altitude. This increase seemed to be related to the greater humidity at altitude. The initial stages of development of the final colonizer, Verticicladium trifidum, were strongly dependent on the first two colonizers on the individual needles. The observed decrease in frequency of V. trifidum with increasing altitude may be due to interactions with the early colonizers, with no direct effect of altitude on V. trifidum. Fungal colonization at low and high altitudes can be interpreted by accounting for both climatic effects and fungal interactions expressed as interference and succession.

Arbuscular mycorrhizal fungi are common in moderately saline soil (colonized by Distichlis stricta) in an inland boreal salt pan in north-central Manitoba, but are absent from adjacent soil that is extremely saline (colonized by Puccinellia nuttalliana). In order to determine if this absence was due to the lack of suitable plant hosts or to edaphic factors, mycorrhizal colonization, vegetation composition, soil salinity and water content were examined along transects between the two vegetation zones. Correlation and principal component analyses revealed that mycorrhizal colonization of P. nuttalliana was positively linked to cover of Distichlis stricta and soil water content, and negatively linked to bare ground. The area closest to the point of salt seepage was uncolonized by mycorrhizal fungi. A transplant experiment confirmed that mycorrhizal fungi are unable to sustain colonization in this area of the salt pan. In this inland salt pan, colonization by mycorrhizal fungi is limited by edaphic factors, and not by the absence of suitable host plants, suggesting that mycorrhizal fungi have a lower limit of salinity tolerance than halophytes such as P. nuttalliana.

Sclerotinia sclerotiorum differentiates by forming terminal-type sclerotia. We found that the fungus produces β-carotene in low and high levels during its undifferentiated and differentiated stages, respectively, and at low (in dark) and high (in light) oxidative growth conditions, respectively. In contrast, a sclerotium non-producing strain of S. sclerotiorum produces very low amounts of β-carotene in constant levels throughout its entire growth period, irrespective of oxidative stress degree of growth conditions. When β-carotene was added to the growth medium of the sclerotium producing strain, it caused a concentration-dependent inhibition of sclerotia formation. We propose that β-carotene inhibits sclerotial differentiation in S. sclerotiorum by lowering oxidative stress via its antioxidant scavenging properties.

The structure and development of galls caused by the heterobasidiomycete Biatoropsis usnearum on Usnea thalli are studied in detail using different microscopical techniques. The galls induced by this fungus are devoid of algae and composed of hyphae of both fungal symbionts. The parasite forms tremelloid haustoria primarily in the central part of the gall. Infections of the parasite start in the cortical layer of the host and induce growth of the host hyphae resembling those of the central cord. The galls include a large amount of intact Usnea hyphae, to some extent also in the uppermost parts of the gall. Mature galls are compared with those caused by other lichenicolous fungi. The investigations show that the anatomies of galls and interactions between host and parasite differ significantly in gall-forming lichenicolous fungi.

Six new taxa of Biscogniauxia are described from Taiwan, including four new species: B. ambiens, B. cylindrispora, B. formosana, and B. latirima; and two new varieties: B. albosticta var. orientalis and B. formosana var. kentingensis. Their cultural and anamorphic data are also provided. A description is provided for B. doidgeae based on its type. Cultural and anamorphic data are given for B. philippinensis var. microspora. A key to the 57 known species of Biscogniauxia in the world is also given.

Cultures of Penzigia cranioides and Poronia pileiformis obtained from material collected in Taiwan produced anamorphs in Xylocoremium and Lindquistia, respectively. The former is reminiscent of those produced by undoubted Xylaria species. Penzigia cranioides, the type species of the genus, is therefore accepted as X. cranioides. Penzigia thus becomes a taxonomic synonym of Xylaria. The position of P. pileiformis in Poronia is considered justified primarily on its anamorph; an epitype is designated.

Inocybe barrasae and I. ortegae spp. nov. from Spain are illustrated and described. Type collections of I. cryptocystis, I. cicatricata, I. dolichospora, I. mystica and I. rennyi were compared with the two, and different interpretations of I. confusa in the literature are discussed.

This revision of cuboid-spored Entoloma in Madagascar is based on the examination of type material described earlier by Romagnesi and new collections made by the first two authors. Entoloma pseudoheimii sp. nov. and E. rufovinascens sp. nov. are described, and two new combinations made: E. cuboidosporum var. chromostomum, and E. heimii combs nov. A key to the madagascarian cuboid-spored species of Entoloma is provided.

The genus Tulasnella is surveyed in the Patagonian Andes forests of southern Argentina based on specimens collected from Austrocedrus chilensis, Nothofagus antarctica, N. betuloides and N. pumilio. Five species are recorded, namely T. robusta sp. nov., T. allantospora s.lat., T. calospora, T. helicospora and T. violea, all of which represent new records for Argentina.